In the cities, there is trash collection. Anywhere outside of the cities, it is dumped just outside of the commune (most of them have a road in and a road out, so there is two heaps). Usually smoldering. If you go to remote areas, you find trash heaps in the middle of nowhere.

It really has nothing to do with money since it is a communist country. The government could decide to allocate resources (ie: people) towards dealing with the mess. That's effectively what they do in the cities.

In Saigon, I lived on Truong Sa in a 5th floor apartment. This street is along a river running through the middle of the city. Every day, there was several boats that would go up and down collecting the trash that people would dump into the river. All day long, I could watch people just stop their bike, get off, walk over to the river and dump their trash into it. The lazy ones would just dump their trash on the street or in the gutters, which tend to back up during rains and cause more flooding.